前提：先搭建好本地的单机运行项目：/EasonJim/p/7643630.html
说明：下面的示例是基于Spring Boot搭建的，对于Spring项目基本通用。迁移旧项目的配置下一篇说明，这里先就如何快速的集成Client和获取配置的值进行实践。
0、下面的示例都是基于官方提供的教程去实践的，可以参考如下网址：
/ctripcorp/apollo/wiki/Java%E5%AE%A2%E6%88%B7%E7%AB%AF%E4%BD%BF%E7%94%A8%E6%8C%87%E5%8D%97
/ctripcorp/apollo/wiki/Apollo%E5%BC%80%E5%8F%91%E6%8C%87%E5%8D%97#23-java%E6%A0%B7%E4%BE%8B%E5%AE%A2%E6%88%B7%E7%AB%AF%E5%90%AF%E5%8A%A8
1、先新建好Spring Boot项目，这里使用了Web做测试，所以引用了Thymeleaf模板。
搭建参考：/EasonJim/p/7519854.html
2、登录Apollo上新建App和相关的配置项，可以参考如下配置：
3、在POM上引入Client的依赖，此时会有两个包引入Client和Core。
<dependency><groupId>com.ctrip.framework.apollo</groupId><artifactId>apollo-client</artifactId><version>0.8.0</version></dependency>
4、在项目上配置上面设置的app.id，注意此时是通过新建META-INF/app.properties文件实现的。
5、代码实现
实现的功能是通过配置中心修改后，再次刷新页面而不重启应用的情况下能看到值的改变。
实现方式主要几种在两种，1为通过API的形式增加监听回调函数来监听值的改变后直接修改，2为通过注入Bean的方式使用Bean下的专用监听注解实现回调监听。
5.1、通过API的方式
代码实现如下：
package com.jsoft.springboottest.springboottest1.controller;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import com.ctrip.framework.apollo.Config;import com.ctrip.framework.apollo.ConfigChangeListener;import com.ctrip.framework.apollo.ConfigService;import com.ctrip.framework.apollo.model.ConfigChange;import com.ctrip.framework.apollo.model.ConfigChangeEvent;import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;@Controllerpublic class IndexController {private static final Logger logger = LoggerFactory.getLogger(IndexController.class);private Config config;private int timeout;private int batch;privateString url;@RequestMapping(value = "/index", method = RequestMethod.GET)public String index(Model model) {Entry entry = new Entry();entry.setText("Text");entry.setTitle("Title");model.addAttribute("entries", entry);model.addAttribute("entry", new Entry());model.addAttribute("url", url);model.addAttribute("timeout",timeout);model.addAttribute("batch",batch);logger.info("timeout:{}", timeout);logger.info("batch:{}", batch);logger.info("url:{}", url);return "index";}public IndexController() {config= ConfigService.getAppConfig();config.addChangeListener(new ConfigChangeListener() {@Overridepublic void onChange(ConfigChangeEvent changeEvent) {logger.info("Changes for namespace {}", changeEvent.getNamespace());for (String key : changeEvent.changedKeys()) {ConfigChange change = changeEvent.getChange(key);logger.info("Change - key: {}, oldValue: {}, newValue: {}, changeType: {}", change.getPropertyName(), change.getOldValue(), change.getNewValue(), change.getChangeType());if (key.equals("url")) {url = change.getNewValue();}if(key.equals("batch")) {batch = Integer.valueOf(change.getNewValue());}if (key.equals("timeout")) {timeout =Integer.valueOf(change.getNewValue());}}}});}}
说明：
通过新建Config对象，使用的是ConfigService.getAppConfig()获取默认配置，也就是配置中心中的application.properties的，当然，getAppConfig可以指定不能的namespage。
通过获取Config对象增加监听回调函数addChangeListener。监听指定的值变化后，重新赋值变量。
这种方式应该是最简单的，不用写特殊的注解去实现，但是可能在运行时也会发现，程序在一启动时不会去获取默认的配置值，比如timeout这些是空的，要解决这个问题时需要在Class上增加@EnableApolloConfig的注解，然后在属性上增加@Value的值即可，改动如下：
package com.jsoft.springboottest.springboottest1.controller;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import com.ctrip.framework.apollo.Config;import com.ctrip.framework.apollo.ConfigChangeListener;import com.ctrip.framework.apollo.ConfigService;import com.ctrip.framework.apollo.model.ConfigChange;import com.ctrip.framework.apollo.model.ConfigChangeEvent;import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;@Controller@EnableApolloConfigpublic class IndexController {private static final Logger logger = LoggerFactory.getLogger(IndexController.class);private Config config;@Value("${timeout:200}")private int timeout;@Value("${batch:200}")private int batch;@Value("${url:}")private String url;@RequestMapping(value = "/index", method = RequestMethod.GET)public String index(Model model) {Entry entry = new Entry();entry.setText("Text");entry.setTitle("Title");model.addAttribute("entries", entry);model.addAttribute("entry", new Entry());model.addAttribute("url", url);model.addAttribute("timeout",timeout);model.addAttribute("batch",batch);logger.info("timeout:{}", timeout);logger.info("batch:{}", batch);logger.info("url:{}", url);return "index";}public IndexController() {config = ConfigService.getAppConfig();config.addChangeListener(new ConfigChangeListener() {@Overridepublic void onChange(ConfigChangeEvent changeEvent) {logger.info("Changes for namespace {}", changeEvent.getNamespace());for (String key : changeEvent.changedKeys()) {ConfigChange change = changeEvent.getChange(key);logger.info("Change - key: {}, oldValue: {}, newValue: {}, changeType: {}", change.getPropertyName(), change.getOldValue(), change.getNewValue(), change.getChangeType());if (key.equals("url")) {url = change.getNewValue();}if(key.equals("batch")) {batch = Integer.valueOf(change.getNewValue());}if (key.equals("timeout")) {timeout = Integer.valueOf(change.getNewValue());}}}});}}
说明：约定俗成，在@Value上获取值时记得增加默认值，以防止获取为空。
上面代码或许有些冗余，可以再提炼一下，因为config对象的值会实时更新，所以也不需要监听onChange事件，也不需要自己创建一个变量，最后代码实现如下：
package com.jsoft.springboottest.springboottest1.controller;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import com.ctrip.framework.apollo.Config;import com.ctrip.framework.apollo.ConfigChangeListener;import com.ctrip.framework.apollo.ConfigService;import com.ctrip.framework.apollo.model.ConfigChange;import com.ctrip.framework.apollo.model.ConfigChangeEvent;import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;@Controllerpublic class IndexController2 {private static final Logger logger = LoggerFactory.getLogger(IndexController2.class);private Config config =ConfigService.getAppConfig();@RequestMapping(value = "/index2", method = RequestMethod.GET)public String index(Model model) {Entry entry = new Entry();entry.setText("Text");entry.setTitle("Title");model.addAttribute("entries", entry);model.addAttribute("entry", new Entry());model.addAttribute("url",config.getProperty("url", ""));model.addAttribute("timeout",config.getProperty("timeout", ""));model.addAttribute("batch",config.getProperty("batch", ""));logger.info("timeout:{}",config.getProperty("timeout", ""));logger.info("batch:{}",config.getProperty("batch", ""));logger.info("url:{}",config.getProperty("url", ""));return "index";}}
5.2、通过注入Bean的方式
5.2.1、新建的Bean如下：
package com.jsoft.springboottest.springboottest1.controller;import com.ctrip.framework.apollo.Config;import com.ctrip.framework.apollo.model.ConfigChange;import com.ctrip.framework.apollo.model.ConfigChangeEvent;import com.ctrip.framework.apollo.spring.annotation.ApolloConfig;import com.ctrip.framework.apollo.spring.annotation.ApolloConfigChangeListener;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Value;import javax.annotation.PostConstruct;public class AnnotatedBean {private static final Logger logger = LoggerFactory.getLogger(AnnotatedBean.class);@Value("${timeout:200}")private int timeout;private int batch;@ApolloConfigprivate Config config;@ApolloConfig("FX.apollo")private Config anotherConfig;@PostConstructvoid initialize() {logger.info("timeout is {}", timeout);logger.info("batch is {}", batch);logger.info("Keys for config: {}", config.getPropertyNames());logger.info("Keys for anotherConfig: {}", anotherConfig.getPropertyNames());}@Value("${batch:100}")public void setBatch(int batch) {this.batch = batch;}public int getBatch() {return batch;}public int getTimeout() {return timeout;}@ApolloConfigChangeListener("application")private void someChangeHandler(ConfigChangeEvent changeEvent) {logger.info("[someChangeHandler]Changes for namespace {}", changeEvent.getNamespace());if (changeEvent.isChanged("timeout")) {refreshTimeout();}if (changeEvent.isChanged("batch")) {setBatch(Integer.valueOf(changeEvent.getChange("batch").getNewValue()));}}@ApolloConfigChangeListener({ "application", "FX.apollo" })private void anotherChangeHandler(ConfigChangeEvent changeEvent) {logger.info("[anotherChangeHandler]Changes for namespace {}", changeEvent.getNamespace());for (String key : changeEvent.changedKeys()) {ConfigChange change = changeEvent.getChange(key);logger.info("[anotherChangeHandler]Change - key: {}, oldValue: {}, newValue: {}, changeType: {}", change.getPropertyName(), change.getOldValue(), change.getNewValue(), change.getChangeType());}}private void refreshTimeout() {// do some custom logic to update placeholder valuetimeout = config.getIntProperty("timeout", timeout);logger.info("Refreshing timeout to {}", timeout);}}
5.2.2、通过@Configuration注入这个Bean，代码如下：
package com.jsoft.springboottest.springboottest1.controller;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import com.ctrip.framework.apollo.spring.annotation.EnableApolloConfig;@Configuration@EnableApolloConfigpublic class AnnotatedConfig {@Beanpublic AnnotatedBean annotatedBean() {return newAnnotatedBean();}}
注意：要增加@EnableApolloConfig和@Configuration，不然不会生效。并且留意到@Bean的注解，如果没有这个时，@ApolloConfigChangeListener不会生效。这个是关键所在，@ApolloConfigChangeListener只能用于Bean注入上，这个和API的方式有明显区别。
在代码上使用：
package com.jsoft.springboottest.springboottest1.controller;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class TestController {private static final Logger logger = LoggerFactory.getLogger(TestController.class);@AutowiredprivateAnnotatedBean annotatedBean;@RequestMapping("/show")public String show(){logger.info("batch:{}",annotatedBean.getBatch());logger.info("timeout:{}",annotatedBean.getTimeout());return "Hello World"+" batch:"+annotatedBean.getBatch()+" timeout:"+annotatedBean.getTimeout(); }}
说明：可以看出，只要@Autowired注入刚才的Bean就可以直接使用。
6、运行，一般只需要在/opt/settings/server.properties中配置了env=DEV就可以直接直接启动（因为Client在本地仓库的包上已经有了meta_server的信息），但是在IDE上也可以通过指定VM的参数，增加系统属性变量-D来实现调试，配置如下：
如果到处JAR运行，直接java -jar Spring-Boot-Demo.jar即可，不需要增加什么参数（但前提是配置了/opt/settings/server.properties的env的值）。
测试代码：/easonjim/5_java_example/tree/master/apollotest/test1
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